Multilayer capacitor

ABSTRACT

First and second external terminal electrodes are formed on the same principal surface of a capacitor main body. The connection between first internal electrodes in the capacitor main body, the first external terminal electrode and the mutual connection between the plurality of first internal electrodes is achieved by a first connection portion. The connection between second internal electrodes, the second external terminal electrode and the mutual connection between the plurality of second internal electrodes is achieved by a second connection portion. The first and second connection portions are arranged alternately. Currents flow through the connection portions in opposite directions with the result that components of magnetic flux generated by such currents are cancelled and the ESL is reduced.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a multilayer capacitor and, moreparticularly, to a multilayer capacitor which can be advantageously usedin high frequency circuits.

[0003] 2. Description of the Related Art

[0004]FIG. 7 shows a schematic sectional view of a typical prior artmultilayer capacitor 1 which includes a main body 5 having a pluralityof ceramic dielectric material layers 2 stacked one on top of the other.A set of first internal electrodes 3 and a set of second internalelectrodes 4 are arranged alternately, with a respective dielectricmaterial layer 2 located between adjacent pairs of electrodes 3 and 4 toform a plurality of capacitor units.

[0005] Each of the first internal electrodes 3 is electrically coupledto a first external terminal electrode 8 formed on a first end face 6 ofthe main body 5. Each of the second internal electrodes 4 iselectrically coupled to a second external electrode 9 formed on a secondend surface 7 of main body 5. As a result, the electrostatic capacitiesrespectively provided by the plurality of capacitor units are connectedin parallel by the first and second external terminal electrodes 8 and9.

[0006] The multilayer capacitor 1 shown in FIG. 7 exhibits a problemwhich is discussed below.

[0007]FIG. 9 is a schematic sectional plan view showing one of theelectrodes 3 of FIG. 7. In this figure, arrows indicate the path anddirection of typical currents 22 which flow in each of the firstinternal electrodes 3 of the multilayer capacitor 1. In the state shown(the directions of the currents alternate over time when an AC signal isapplied to the capacitor), the currents 22 flow from the second externalelectrode 9 to the second internal electrodes 4 (not shown in FIG. 9),vertically to the first internal electrodes 3 through the dielectricmaterial layers 2 and then to the first external terminal electrode 8through the first internal electrodes 3. There is a general flow ofcurrents in both internal electrodes 3 and 4 from right to left, i.e.,in the same direction, as seen in FIG. 9.

[0008] As is well known, the current 22 induces a magnetic flux in adirection determined by the direction of the current 22, therebyproducing a self-inductance component. Since the currents 22 flow in thelongitudinal direction of the internal electrodes 3, the multilayercapacitor 1 produces relatively high equivalent series inductance (ESL)and may fail to function properly in a high frequency band when it isused as a decoupling capacitor or bypass capacitor.

[0009] This problem is partly overcome using the structure shownschematically in FIG. 8. This structure is described in Japaneseunexamined patent publication No. H7-201651.

[0010] Like the multilayer capacitor 1 shown in FIG. 7, the multilayercapacitor 11 includes a main body 15 having a plurality of dielectricmaterial layers 12 stacked one on top of the other. A plurality of firstinternal electrodes 13 and a plurality of second internal electrodes 14are arranged on respective dielectric material layers 12 to form pairsof overlapping electrodes, each pair of overlapping electrodes beingseparated by a respective dielectric material layer 12 such that aplurality of capacitor units are formed.

[0011] In this multilayer capacitor 11, first and second externalterminal electrodes 18 and 19 are formed, respectively, on first andsecond principal surfaces 16 and 17 extending in parallel with theinternal electrodes 13 and 14.

[0012] A plurality of first connection portions 20, which areelectrically isolated from second internal electrodes 14, are providedto electrically connect the first internal electrodes 13 to both thefirst external terminal electrode 18 and to each other.

[0013] A plurality of second connection portions 21, which areelectrically isolated from first internal electrodes 13, are provided toelectrically connect the second internal electrodes 14 to both thesecond external terminal electrode 19 and each other.

[0014] Thus, the electrostatic capacities provided by the plurality ofthe capacitor units formed by the respective pairs of internalelectrodes 13 and 14 are coupled in parallel by the connection portions20 and 21 and are combined at external terminal electrodes 18 and 19,respectively.

[0015] Compared to the prior art capacitor of FIG. 7, the multilayercapacitor 11 shown in FIG. 8 reduces the equivalent series inductance(ESL) and is suitable for use in a high frequency band.

[0016] In FIG. 10, the arrows indicate the path and direction of typicalcurrents 23 which flow in, for example, the first internal electrodes 13of the multilayer capacitor 11. In the state shown (the directions ofthe currents alternate over time when an AC signal is applied to thecapacitor), the currents 23 flow from the second internal electrodes 14(not shown in FIG. 10) in a face-to-face relationship with the firstinternal electrodes 13 to the first internal electrodes 13 through thesecond connection portions 21. Then, most of the currents flow to thenearest first connection portion 20 and further to the first externalterminal electrode 18 through the first connection portion 20.

[0017] When such a flow of the currents 23 is viewed with attention tothe area around the connection portions 20 or 21, since the currents 23flow in various directions, components of magnetic flux produced by thecurrents 23 are advantageously canceled by each other to suppress thegeneration of net magnetic flux. Further, since the lengths of the pathsof the currents 23 flowing through the internal electrodes 13 or 14 arelimited to the intervals between adjacent connection portions 20 and 21,the lengths of each of the current paths is relatively short and,therefore, the self-inductance components produced are reduced.

[0018] However, the reduction of the ESL in the multilayer capacitor 11is achieved only for components of magnetic flux induced by the currents23 in the direction in which the internal electrodes 13 and 14 extend.FIG. 11 is an enlarged view of a part of the multilayer capacitor 11shown in FIG. 8, in which currents 24 and 25 flowing respectivelythrough the connection portions 20 and 21 of the multilayer capacitor 11are indicated by the dashed arrows.

[0019] Referring to FIG. 11, when currents flow, for example, from thesecond external terminal electrode 19 to the first external terminalelectrode 18, upwardly directed currents 24, 25 flow through both thefirst connection portions 20 and through the second connection portions21, respectively.

[0020] The currents 24 flowing through the first connection portion 20and the currents 25 flowing through the second connection portion 21produce respective components of magnetic flux 26 and 27, as shown inFIG. 12. The currents flowing through the respective connection portions20 and 21 flow from the back side to the front side of the plane of FIG.12 (i.e., they flow out of the page). The direction of the resultantcomponents of magnetic flux 26 and 27 oppose one another in the areasbetween the connection portions 20 and 21. As a result, the magneticflux is canceled between the connection portions 20 and 21.

[0021] The magnetic flux 28 that surrounds the components of magneticflux 26 and 27, however, is not cancelled.

[0022] Rather, the magnetic flux 28 tends to be greater than eachindividual magnetic flux 26, 27 and, therefore, increases the ESL.

[0023] As a result, the components of magnetic flux 26 and 27 producedby the currents 24 and 25 flowing through the connection portions 20 and21 are not effectively canceled and increase the self-inductance of thecapacitor 11. Thus, the ESL is not sufficiently reduced and highfrequency performance is not sufficiently improved.

SUMMARY OF THE INVENTION

[0024] In order to solve the above-described technical problems, amultilayer capacitor according to the present invention comprises acapacitor body; m pair of first and second generally planar internalelectrodes located in said capacitor body, each said pair of internalelectrodes being separated by a respective dielectric layer to define arespective capacitive unit, m being a positive integer greater than orequal to one. The multilayer capacitor also comprises n first externalelectrodes located on a first surface of said capacitor body, n being aninteger greater than or equal to 1; p second external electrodes locatedon said first surface of said capacitor body, p being an integer greaterthan or equal to 1; n first connection portions operable to electricallyconnect said first internal electrodes to each other and to a respectiveone of said first external electrodes, each of said first connectionportions being electrically insulated from said second internalelectrodes; and p second connection portions operable to electricallyconnect said second internal electrodes to each other and to arespective one of said second external electrodes, each of said secondconnection portions being electrically insulated from said firstinternal electrodes.

[0025] According to the invention, the first and second connectionportions are arranged such that they are not more than about 2 mm fromeach other. Preferably, they are not positioned more than about 1 mmapart. In other words, the interval between the first and secondconnection portions is preferably as small as possible.

[0026] Further, according to the invention, it is preferable that aplurality of first and second connection portions are provided.

[0027] In the preferred embodiment of the invention described above, theplurality of first connection portions and the plurality of secondconnection portions are more preferably arranged such that theconnection portions nearest to each of the first connection portion aresecond connection portions.

[0028] More preferably, the plurality of first connection portions andthe plurality of second connection portions are alternately arranged.

[0029] Further, the first and second internal electrodes are preferablydisposed in a substantially square configuration and are rounded in theareas of the four corners of the square. Still further, each of thefirst and second connection portions preferably has a substantiallyround configuration, and the roundness at the corners of the first andsecond internal electrodes is provided as an arc which is substantiallyconcentric with the sectional configuration of the first or secondconnection portions which are nearest to the relevant corners.

[0030] Moreover, according to the invention, the first and secondexternal terminal electrodes are preferably in a substantiallypoint-like configuration.

[0031] In a preferred embodiment of the invention, a plurality of firstand second internal electrodes are provided such that they arealternately arranged in the stacking direction of the dielectricmaterial layers; the first connection portion further extends throughthe second internal electrodes to electrically connect the plurality offirst internal electrodes to each other; and the second connectionportion further extends through the first internal electrodes toelectrically connect the plurality of second internal electrodes to eachother.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] For the purpose of illustrating the invention, there is shown inthe drawing a form which is presently preferred, it being understood,however, that the invention is not limited to the precise arrangementand instrumentality shown.

[0033]FIG. 1 is a perspective view of a multilayer capacitor 31according to a first embodiment of the invention.

[0034]FIG. 2 is a schematic cross section of the capacitor 31 takenalong lines 2-2 of FIG. 1.

[0035]FIG. 2A is a more detailed view of dashed area 2A of FIG. 2.

[0036]FIG. 3 is a schematic cross sectional view of the multilayercapacitor 31 shown in FIG. 1 taken along lines 3-3 of FIG. 1 which showsa first internal electrode 33.

[0037]FIG. 4 is a cross sectional view of the multilayer capacitor 31shown in FIG. 1 taken along lines 4-4 of FIG. 1 which shows a secondinternal electrode 34.

[0038]FIG. 5 is a schematic view of the multilayer capacitor 31 shown inFIG. 1 which illustrates currents 44 and 45 flowing through first andsecond connection portions 40 and 41 thereof, respectively.

[0039]FIG. 6 is a schematic view illustrating components of magneticflux 46 and 47 induced by the currents flowing through the first andsecond connection portions 40 and 41 shown in FIG. 5, respectively.

[0040]FIG. 7 is a front schematic view of a conventional multilayercapacitor 1 which shows an internal structure thereof in the form of avertical section.

[0041]FIG. 8 is a front schematic view of another conventionalmultilayer capacitor 11 which shows an internal structure thereof in theform of a vertical section.

[0042]FIG. 9 is a schematic view illustrating currents 22 flowingthrough internal electrodes 3 of the multilayer capacitor 1 taken alonglines 9-9 of FIG. 7.

[0043]FIG. 10 is a partial cross sectional view illustrating currents 23flowing through internal electrodes 13 of the multilayer capacitor 11shown in FIG. 8.

[0044]FIG. 11 is a schematic view of the multilayer capacitor 11 shownin FIG. 8 illustrating currents 24 and 25 flowing through first andsecond connection portions 20 and 21, respectively.

[0045]FIG. 12 is a schematic view illustrating components of magneticflux 26 and 27 induced by the currents flowing through the first andsecond connection portions 20 and 21 shown in FIG. 11, respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0046] Referring now to the drawings wherein like numerals indicate likeelements, there is shown in FIGS. 1 through 4 a multilayer capacitorconstructed in accordance with the principles of the present inventionand designated generally as 31.

[0047] The multilayer capacitor 31 includes a capacitor main body 35having a plurality of dielectric material layers 32 (FIGS. 2, 2A)preferably made of a ceramic dielectric material and a plurality ofpairs of opposed first and second internal electrodes 33 and 34, eachsuch pair of opposing internal electrodes having a dielectric materiallayer 32 interposed therebetween, so as to form a plurality of capacitorunits.

[0048] The capacitor main body 35 may be manufactured, for example, byforming internal electrodes 33 and 34 on a plurality of ceramic greensheets, stacking them one on top of the other, and then pressing andcutting the ceramic green sheets to obtain raw chips each having a sizecorresponding to one capacitor main body 35 and then baking them.

[0049] Like the multilayer capacitor of FIG. 8, the multilayer capacitor31 electrically couples the first and second internal electrodes using aplurality of connection portions 40, 41. Unlike the multilayer capacitorof FIG. 8, the external electrodes 38, 39 coupled to connection portions40, 41, respectively, are formed on the same outer surface 37 of thecapacitor body 35 to ensure counter current flow in connection portions40, 41 and thereby to reduce the ESL.

[0050] As best shown in FIGS. 2 and 2A (where FIG. 2A is a detailedcross-sectional view of the schematic cross-section of multilayercapacitor 31 shown in FIG. 2), the first connection portions 40 extendthrough the dielectric layers 32 and are electrically coupled to each ofthe first internal electrodes 33. As best shown in FIGS. 2A and 3, firstconnection portions 40 pass through openings 42 in the second internalelectrodes 34 and are electrically insulated therefrom.

[0051] In a similar manner, second connection portions 41 extend throughthe dielectric layers 32 and are electrically coupled to each of thesecond internal electrodes 34. As best shown in FIGS. 2A and 4, secondconnection portions 41 pass through openings 43 in the first internalelectrodes 34 and are electrically insulated therefrom.

[0052] The connection portions 40 and 41 may be formed, for example, byforming holes in the ceramic green sheets before they are laminatedtogether and filling the holes with conductive paste before they arestacked one on top of the other.

[0053] In the present embodiment, currents flow through internalelectrodes 33 and 34 in substantially the same manner as the prior artof FIG. 8 (i.e., as shown in FIG. 10) Since the currents flow in variousdirections in the region around each of the connection portions 40 and41, components of magnetic flux produced by the currents areadvantageously canceled and the generation of a net magnetic flux issuppressed. Further, since the lengths of the paths of the currentsflowing through the internal electrodes 33 and 34 are limited to theintervals between adjacent connection portions 40 and 41, each of thecurrent lengths are relatively short and, therefore, the self-inductancecomponents produced at such intervals is reduced.

[0054] Further, as best shown in FIGS. 3 and 4, the first and secondinternal electrodes 33 and 34 of the present embodiment have asubstantially rectangular configuration. In the preferred embodiment,the regions of the four corners of the rectangle are rounded with an arcwhich is substantially concentric with the center of the first or secondconnection portions 40 and 41 which are nearest to the relevant corner.Thus, the distance between the edge at each of the corners of the firstand second internal electrodes 33 and 34 and the first or secondconnection portion 40 or 41 nearest to the corner is smaller than whenthe corners are not rounded. This also results in a reduction of thecurrent length and contributes to a reduction in the ESL.

[0055] Where it is not necessary to minimize the inductance, theelectrodes may be replaced with internal electrodes 33 a and 34 a whosecorners are not rounded as indicated by the imaginary lines in FIGS. 3and 4.

[0056]FIG. 5 is an enlarged schematic view of a part of the multilayercapacitor 31 shown in FIG. 2. It is a view corresponding to FIG. 11 inwhich the dashed arrows indicate currents 44 and 45 flowing through theconnection portions 40 and 41 of the multilayer capacitor 31,respectively.

[0057] When a current flows, for example, from the first externalterminal electrode 38 to the second external terminal electrode 39,upward currents 44 flow through the first connection portions 40 whiledownward currents 45 flow through the second connection portions 41.That is, the currents 44 flowing through the first connection portions40 flow in the opposite direction with respect to the currents 45flowing through the second connection portions 41.

[0058] As a result, the respective currents 44 and 45 flowing throughthe first and second connection portions 40 and 41 (FIG. 6) producerespective components of magnetic flux 46 and 47 which are in oppositedirections. In FIG. 6, the currents 44 flowing through the firstconnection portions 40 flows from the back side to the front side of theplane of the paper, and the currents 45 flowing through the secondconnection portions 41 flow from the front side to the back side of theplane of the paper.

[0059] Therefore, the components of magnetic flux 46 and 47 areeffectively canceled by each other outside the connection portions 40and 41. The components of magnetic flux 46 and 47 extend in the samedirection in the areas between the connection portions 40 and 41 and,therefore, overlap with each other in these limited areas. However,since these areas are relatively small, they have only a limitedmagnetic flux density with the result that the components of magneticflux 46 and 47 are effectively canceled by each other when viewed as awhole.

[0060] In order to improve the degree of the cancellation between thecomponents of magnetic flux 46 and 47 described above, it is preferablethat the intervals (or distances) between the first and secondconnection portions 40 and 41 be small, preferably about 2 mm or less.Even better results are achieved if the intervals are about 1 mm orless.

[0061] Thus, the present embodiment makes it possible to effectivelycancel the components of magnetic flux induced by the currents whichflow through internal electrodes 33 and 34 and those which flow throughconnection portions 40 and 41. Therefore, it is possible to suppress theESL of the multilayer capacitor 31 to a higher degree than is possiblein the conventional multilayer capacitor 11 shown in FIG. 8.

[0062] Samples of the multilayer capacitor 31 according to the presentembodiment (“present embodiment”), the conventional multilayer capacitor1 shown in FIG. 7 (“comparative example 1”) and the conventionalmultilayer capacitor 11 shown in FIG. 8 (“omparative example 2”) werefabricated and their ESLs were evaluated.

[0063] In each of the samples, the outer dimensions of the internalelectrodes were b 5 mm×5 mm and a total of forty (40) internalelectrodes were stacked one on top of the other. In the presentembodiment and the comparative example 2, the first and secondconnection portions were provided so as to form five rows and fivecolumns totalling twenty-five (25) connection portions. The intervalsbetween each of the first and second connection portions (the centerlateral distance between each pair of adjacent connection portions) was1 mm.

[0064] The ESL of each sample was obtained using the resonance method.The resonance method is a method wherein the impedance frequencycharacteristics of each sample multilayer capacitor is measured and theESL is obtained by measuring a frequency f₀ at a minimum resonance point(referred to as the series resonance point of the capacitance componentC₃ and the ESL of the capacitor). The following equation is then used tocalculate the ESL:

ESL=1/[(2πf ₀)² ×C ₃]

[0065] The measured value of ESL of each of the samples is shown inTable 1 below. TABLE 1 ESL Value (pH) Present Embodiment 26 ComparativeExample 1 590 Comparative Example 2 73

[0066] It is apparent from Table 1 that the ESL was reduced moreeffectively with the structure of the present embodiment than with thestructure of either of the comparative examples 1 or 2. While it isapparent that the components of magnetic flux induced by currentsflowing through the internal electrodes of the comparative example 2 wascanceled more efficiently than in the comparative example 1, it will beunderstood that it had a high self-inductance compared to the presentembodiment. This is because the currents in comparative example 2 flowthrough the first and second connection portions in the same direction.Conversely, the currents in the present embodiment flow through thefirst and second connection portions in opposite directions.

[0067] To determine the best arrangement of the connection portions 40,41 of the present invention, additional tests were conducted. In each ofthe test samples, a multilayer capacitor 31 was fabricated with the samenumber of stacked layers using the same method of fabrication. Foursamples 1 through 4 were fabricated in which the arrangement of theconnection portions 40 and 41 was changed, i.e., the numbers of the rowsand columns and the intervals (spacing) of the connection portions 40and 41 were changed as shown in Table 2 (below). In each of thesesamples, the interval between the outermost connection portions and theperipheral edges of the inner electrodes was fixed at 0.5 mm in order toeliminate, to the degree possible, the effect of any variation of thisinterval.

[0068] For the samples 1, 3 and 4, the outer dimensions of each internalelectrode were fixed, e.g., at 5 mm×5 mm and the interval of theconnection portions was varied as shown in Table 2. The sample 4corresponds to the embodiment shown in FIGS. 1-4. For the sample 2, theouter dimensions of each internal electrode were made smaller than thoseof sample 1 (i.e., 4 mm×4 mm), and the number of the connection portionswas set at “2×2” such that an interval of 3 mm was obtained as shown inTable 2.

[0069] Table 2 shows an ESL value measured for each of theabove-described samples using the resonance method. TABLE 2 Row × ColumnInterval (mm) ESL Value (pH) Sample 1 2 × 2 4 360 Sample 2 2 × 2 3 340Sample 3 3 × 3 2 58 Sample 4 5 × 5 1 26

[0070] As apparent from Table 2, changes in the arrangement of theconnection portions, especially changes in the interval therebetween,cause changes in the path lengths of the currents flowing through theinternal electrodes and, therefore, the strength of the components ofmagnetic flux induced thereby is likewise altered. This accounts for thedifferences between the measured ESL values for the samples. While aninterval between the connection portions of 3 mm or more (as in samples1 and 2) provides a less significant reduction in ESL, an interval of 2mm or less (as in samples 3 and 4) results in a significant reduction ofthe ESL value due to the cancellation of the components of magneticflux. The result is even more favorable when the interval is 1 mm orless, as in sample 4.

[0071] While the present invention has been described by way of examplewith reference to the illustrated embodiment, it is possible to change:the number of the internal electrodes, the number and positions of theconnection portions, and the number and positions of the externalterminal electrodes and still remain within the scope of the invention.Further, the type of the dielectric material used for the dielectriclayers and the type of the conductive material used for the internalelectrodes and external terminal electrodes may be changed asappropriate.

[0072] As described above, a multilayer capacitor according. to thepresent invention comprises a capacitor main body including a pluralityof dielectric material layers which are stacked one on top of the otherand at least a pair of first and second internal electrodes which are ina face-to-face relationship with each other with dielectric materiallayers interposed therebetween. First and second external terminalelectrodes are formed on one principal surface of the capacitor mainbody extending parallel to the plane of the internal electrodes. A firstconnection portion penetrates through the dielectric material layerssuch that it electrically connects the first internal electrodes and thefirst external terminal electrode while being electrically isolated fromthe second internal electrodes. A second connection portion is disposedadjacent to the first connection portion and penetrates through thedielectric material layers such that it electrically connects the secondinternal electrodes and the second external terminal electrode whilebeing electrically isolated from the first internal electrodes.

[0073] As a result, by directing the currents in each of the internalelectrodes in various directions around the connection portions,components of magnetic flux can be effectively canceled and the lengthsthat the currents must flow can be shortened to suppress the ESL. Inaddition, since both of the first and second external terminalelectrodes are formed on the same principal surface of the capacitormain body, the currents flowing through the first connection portionsflow in a direction opposite to those that flow through the adjacentsecond connection portions. This makes it possible to effectively cancelthe components of magnetic flux induced by the currents flowing throughthe connection portions, and to further reduce the ESL.

[0074] As a result, a high resonance frequency can be achieved, and thecapacitor can be used in a high frequency circuit. Accordingly, amultilayer capacitor according to the invention can be used inelectronic circuits operating at higher-frequencies and can beadvantageously used as a bypass capacitor or decoupling capacitor in ahigh frequency circuit. Because of the low ESL, the invention willfunction as a quick power supply supplying power from electricity storedin the capacitor when there is a sudden need for power, for example,during power-up. As such, the invention can be used as a decouplingcapacitor in a CPU (microprocessing unit).

[0075] According to the invention, the degree to which magnetic flux iscancelled in the capacitor is significantly improved when the intervalbetween the first and second connection portions is 2 mm or less. Thedegree of the magnetic flux cancellation is further improved as theinterval is reduced to 1 mm or less which allows the ESL value to bereduced to 30 pH or less.

[0076] For high speed CPU's, operation in excess of 1 GHz are beingstudied. There is a need for decoupling capacitors having an ESL valueof 30 pH or less which has been unachievable in the prior art for use inthe vicinity of such processor units. A multilayer capacitor accordingto the invention can sufficiently satisfy such a need because its ESLcan be reduced to 30 pH or less.

[0077] According to the invention, when plurality of first and secondconnection portions are provided, it is possible to more easily directthe currents in each internal electrode in various directions around theconnection portions connected thereto and to shorten the lengths of thecurrent paths.

[0078] When the connection portions are arranged such that each firstconnection portion is located closest to a corresponding secondconnection portion, the magnetic flux components induced by the currentsflowing through the connection portions can be canceled moreeffectively. When the plurality of first and second connection portionsare arranged alternately, the most effective cancellation of magneticflux components can be achieved.

[0079] When the shape of the internal electrodes are substantiallysquare with rounded corners, the distance between the corner edge of theinternal electrodes and the connection portion located closest to thecorner edge can be minimized versus when the corner is not rounded. Thisfunctions to further reduce the lengths of the current paths and,therefore, contribute further to the reduction of the ESL.

[0080] This effect can be further enhanced by forming each of the firstand second connection portions with a substantially circularcross-section and by forming the rounded corners of the internalelectrodes in an arc which is substantially concentric with the circularcross-section of the connection portion nearest to the corner.

[0081] Furthermore, when the first and second external terminalelectrodes of the invention are bump-like in shape, a bump connectioncan be advantageously used to mount the multilayer capacitor to acircuit board. There is a trend toward the use of such bump connectionsin semiconductor chips (such as CPUs, “flip chips” or the like), whichchips have higher operational frequencies. The configuration of theexternal terminal electrodes as described above is consistent with thistrend. Such bump connection allows mounting with a high density andmakes it possible to suppress the generation of inductance components atthe connections.

[0082] In addition, while a plurality of first and second internalelectrodes are alternately arranged in the stacking direction of thedielectric material layers in order to increase the electrostaticcapacity provided, the above-described effects can be achieved in amultilayer capacitor having such an increased capacity by forming thefirst connection portions such that they do not electrically connect thesecond internal electrodes but electrically connect the plurality offirst internal electrodes to each other and by forming the secondconnection portions such that they do not electrically connect the firstinternal electrodes but electrically connect the plurality of secondinternal electrodes to each other.

[0083] It should be understood that the foregoing description is onlyillustrative of the invention. Various alternatives and modificationscan be devised by those skilled in the art without departing from theinvention. Accordingly, the present invention is intended to embrace allsuch alternatives, modifications and variances which fall within thescope of the appended claims.

What is claimed is:
 1. A capacitor, comprising: a capacitor body; m pairof first and second generally planar internal electrodes located in saidcapacitor body, each said pair of internal electrodes being separated bya respective dielectric layer to define a respective capacitive unit, mbeing a positive integer greater than or equal to one; n first externalelectrodes located on a first surface of said capacitor body, n being aninteger greater than or equal to 1; p second external electrodes locatedon said first surface of said capacitor body, p being an integer greaterthan or equal to 1; n first connection portions operable to electricallyconnect said first internal electrodes to each other and to a respectiveone of said first external electrodes, each of said first connectionportions being electrically insulated from said second internalelectrodes; p second connection portions operable to electricallyconnect said second internal electrodes to each other and to arespective one of said second external electrodes, each of said secondconnection portions being electrically insulated from said firstinternal electrodes.
 2. The capacitor of claim 1, wherein said first andsecond connection portions are arranged such that when an alternatingcurrent is applied to said first and second external electrodes,components of flux created by currents flowing in said first and secondconnection portions oppose one another.
 3. The capacitor of claim 1,wherein n and p are positive integers greater than 1 and said first andsecond connection portions are arranged such that each of said firstconnection portions is located adjacent at least one of said secondconnection portions and current flows through said first and secondconnection portions in opposite directions when an alternating currentis applied to said first and second external electrodes.
 4. Thecapacitor of claim 1, wherein said capacitor body has a generallyparallelpiped shape.
 5. The capacitor of claim 1, wherein saidconnection portions extend parallel to one another.
 6. The capacitor ofclaim 5, wherein said connection portions are arranged such that alateral spacing between adjacent ones of said connection portions isabout 2 mm or less.
 7. The capacitor of claim 6, wherein said lateralspacing between adjacent ones of said connection portions is about 1 mmor less.
 8. The capacitor of claim 5, wherein each of said firstconnection portions is located adjacent at least one of said secondconnection portions.
 9. The capacitor of claim 8, wherein each of saidfirst connection portions is located laterally closer to respective onesof said second connection portions than they are to any remaining saidfirst connection portions.
 10. The capacitor of claim 5, wherein each ofsaid connection portions extends in a direction perpendicular to saidgenerally planar first and second internal electrodes.
 11. The capacitorof claim 1, wherein each of said first and second internal electrodeshave rounded corners.
 12. The capacitor of claim 1, wherein each of saidfirst and second internal electrodes is generally rectangular in shapeand has four corners, and wherein each of said corners is rounded. 13.The capacitor of claim 12, wherein each of said rounded corners has arespective first or second connection portion located adjacent thereto.14. The capacitor of claim 13, wherein a portion of each connectionportion which located adjacent one of said rounded corners includes around cross section having a center which is substantially concentricwith a radius of the adjacent rounded corner.
 15. The capacitor of claim1, wherein said first connection portions pass through respective holesformed in said second internal electrodes and said second connectionportions pass through respective holes formed in said first internalelectrodes.
 16. The capacitor of claim 15, wherein dielectric materialis located between portions of said first and second connection portionswhich pass through said holes in said second internal electrodes andsaid first internal electrodes, respectively.
 17. The capacitor of claim1, wherein m, n and p are all positive integers greater than
 1. 18. Thecapacitor of claim 1, wherein each of said external electrodes has abutton-like shape.
 19. A capacitor, comprising: a capacitor body; m pairof first and second generally planar internal electrodes located in saidcapacitor body, each said pair of internal electrodes being separated bya respective dielectric layer to define a respective capacitive unit, mbeing a positive integer greater than or equal to one; n first externalelectrodes, n being an integer greater than or equal to 1; p secondexternal electrodes, p being an integer greater than or equal to 1; nfirst connection portions each electrically connecting said firstinternal electrodes to each other and is to a respective one of saidfirst external electrodes, said first connection portions beingelectrically insulated from said second internal electrodes; p secondconnection portions each electrically connecting said second internalelectrodes to each other and to a respective one of said second externalelectrodes, said second connection portions being electrically insulatedfrom said first internal electrodes; each of said connection portionsextending parallel to the other of said connection portions, the spacingbetween each of said connection portions as measured along a directionperpendicular to the direction in which said connection portions extendis about 2 mm or less.
 20. The capacitor of claim 19, wherein saidspacing is about 1 mm or less.
 21. The capacitor of claim 19, whereinsaid first and second connection portions and said external electrodesare arranged such that components of flux created by currents flowing insaid first and second connection portions oppose one another when analternating current is applied to said first and second externalelectrodes.
 22. The capacitor of claim 19, wherein n and p are positiveintegers greater than 1 and said first and second connection portionsare arranged such that each of said first connection portions is locatedadjacent at least one of said second connection portions and currentflows through said first and second connection portions in oppositedirections when an alternating current is applied to said first andsecond external electrodes.
 23. The capacitor of claim 19, wherein saidcapacitor body has a generally parallelpiped shape.
 24. The capacitor ofclaim 19, wherein each of said first connection portions is locatedadjacent at least one of said second connection portions.
 25. Thecapacitor of claim 24, wherein each of said first connection portions islocated laterally closer to respective ones of said second connectionportions than they are to any remaining said first connection portions.26. The capacitor of claim 19, wherein each of said connection portionsextend in a direction perpendicular to said generally planar first andsecond internal electrodes.
 27. The capacitor of claim 19, wherein eachof said first and second internal electrodes have rounded corners. 28.The capacitor of claim 19, wherein each of said first and secondinternal electrodes is generally rectangular in shape and has fourcorners, each of said corners being rounded.
 29. The capacitor of claim28, wherein each of said rounded corners has a respective first orsecond connection portion located adjacent thereto.
 30. The capacitor ofclaim 29, wherein a portion of each connection portion which is locatedadjacent one of said rounded corners includes a round cross sectionhaving a center which is substantially concentric with a radius of theadjacent rounded corner.
 31. The capacitor of claim 19, wherein saidfirst connection portions pass through respective holes formed in saidsecond internal electrodes and said second connection portions passthrough respective holes formed in said first internal electrodes. 32.The capacitor of claim 31, wherein dielectric material is locatedbetween portions of said first and second connection portions which passthrough said holes in said second internal electrodes and said firstinternal electrodes, respectively.
 33. The capacitor of claim 19,wherein m, n and p are all positive integers greater than
 1. 34. Thecapacitor of claim 19, wherein each of said external electrodes hasbutton-like shape.